Small engine ratings

[geo in mi]

Can someone explain the new small engine ratings? What used to be in horsepower is now in something else, but I don't understand the terminology. Is there a table of equivalents anywhere that would help?

[o&itw]

It would be great to get some kind of table on the different "versions" of horsepower, too. I don't really understand how a scientific term that should be fixed, can very so widely for the same engine. Hope someone on here with the expertise will share.

[ace admirer]

even the octane rating you see at the pump is a "lie" ever wonder what the formula written under the octane rating means? octane rating = rm+lm/2

accountants can bend any engineering facts to profit.

[Beeman]

Nothing means anything or in any way relates to what we had as a standard all of our lives.
I have a friend that's a tractor mechanic for a name brand tractor dealer. He said most trators now have false HP ratings unless they are rated as Agriculture tractors. All of the rest are utility tractors and don't meet HP standards as we've known for years. This isn't just small tractors but even larger size tractors.

[agmantoo]

The cc numbers are nearly meaningless. Divide the cc by 15 and you will get a near horsepower. Air compressor manufacturers are one of the worst when it comes to giving info for output. The HP given on the unit is totally meaningless. The motors used are rated in a manner that is also meaningless. The CFM output of the compressor is seldom understood by the buyer. This is all intentional. In air compressors it is best to remember that a good design of compressor should deliver 4 CFM/HP at 100 PSI. Many small compressors sold to be 3 to 5 HP actually only deliver the equivalent to a 1 1/2 machine. A gallon can of paint at the box stores now only contain 9/10ths of a gallon. One needs to be an informed consumer before making any purchases.

[spiritrider]

Just another way of stating output or work done.

1 kw = 1.34 hp, 1 hp = .745 kw

How accurate the manufacturers inflated guess is, who knows.

Displacement will only get you a swag, I've seen 614 cc engine rated 16-18+ hp.

Carburation and exhaust configurations can make a big difference.

spiritrider

[geo in mi]

Originally Posted by ace admirer

even the octane rating you see at the pump is a "lie" ever wonder what the formula written under the octane rating means? octane rating = rm+lm/2

accountants can bend any engineering facts to profit.

Hey, wait a sec....I uster be a accountant...........

They always said you can't get blood out of a turnip, but give it to an accountant and he'll give you something that looks like blood

But then, I never saw five horses pulling a rototiller, either.....

[ace admirer]

Geo in mi,,,,i admire the creativity of your science...

first off 1 hp is not a horsepower,,,,,the animal Watt used was a pony used in mining operations.. the weight lifted was a mining ore car.

the 746 watt = i hp is just a mechanical to electrical equal

there is brake hp,,,,,a "pony" brake (friction) was used to test mechanical hp.....if the dyno operator slams the brake down the flywheel effect of the motor/engine will record higher than actual. (sears craftsman saw: "develops 2 1/2 hp" in other words, get the saw up to speed, then jam it into a load and it cuts for 1/2 second as if it had 2 1/2 hp.
Friction dyno later replaced with water pump, now electrical generator/loadbank.

on the dyno, take the water pump off, no belts, light viscosity oil, opp temp, humidity, no filter, lower oil pump pressure, opp exhaust scavaging with no back pressure, no mechanical fuel pump. all the little auxs, that are needed to run an engine are removed to increase dyno'd readings....

then realize that hp rating means nothing without actually looking at the torque vs rpm curve.... without that, you might as well just say that our motor is mobetter than theirs....cause its prettier.

on tractors,,pto hp, thats hp at the tail end of the tractor to power machinery. Drawbar hp, thats hp at the wheels after going through the gearbox and final drive... all more accurate than brake hp....want real tractor hp,,,read Nebraska tractor test....those guys did in depth actual testing of tractors and published them. everything from walkbehind tillers to BIG stuff.

have you looked closely at light bulbs lately (those of you that still use them) it might say 100 WATTS but in small print @130 volts... so its a "lie" who has 130 volts at their house,,,,,its going to be lower around 120 volts right? so the 100 watt bulb is not 100 watts....its around 93 watts....very creative...

i keep telling my kids for every person trying to make an honest buck, there are thousands figuring a way to steal it.